The Deep Sea – an explorer’s paradise

Exploring the depths of deep-sea mining. In this series we will explore the science and glory of the deep sea, so that you and I can both go away with knowledge and juicy facts at our fingertips. Continuing this exploration we shall look into the regulations and politics of deep sea mining, as well as the attention we must all pay to prevent further disasters.

The Deep Sea – an explorer’s paradise
'Beauty of deep sea species' by @milie.dsgn for WISE. © 2021 Emilie Schaefer and What Is Science Even?

“There’s no way this can be stopped”

Said our guest Lecturer, as he looked scathingly around at us guiltily tippy taping on our laptops, illuminated by a further eight screens around the walls each projecting the same power point slide, highlighting the shame on our faces at such wasteful technological use. What was the cause of his gloom and doom, however? Something that has been developing generally beyond the public’s knowledge: Deep Sea Mining.

In this three-part series we are going to explore the wonders and mysteries of the deep sea; the potential impacts of mining should it take place, before delving into the politics and policies surrounding this contentious issue.

So, let’s start digging a little deeper…


The deep sea – an explorer’s paradise

The deep sea is the lowest layer of the ocean. Starting at a depth of 200 m it can plunge down to a staggering 11,000 m in the Mariana Trench. As a quick illustration, Mount Everest is 8,900 m. So pop Mount Snowdon on top of Everest, three times, and we’re reaching the deepest depths of the ocean. What’s crazy is that three people have now been to this point. While this is the most overlooked habitat (understandably, seeing as we can conveniently bob over), it is in fact the largest one on the planet covering 96% of the earth. This vast expanse is not just a flat muddy bottom. It is as diverse and fantastic as our terrestrial habitats. This textured and miscellaneous patchwork of continents constitutes steep sided canyons, continental slopes generating ocean upwellings (the circulation of cold nutrient-rich waters lifting to replace warmer, nutrient depleted surface waters) and currents, mid-ocean ridges as creviced and rugged as mountain ranges, volcanic seamounts blanketed by cold-water coral reefs [1] and deep trenches sat alongside abyssal plains [2]. An explorer’s paradise.

This psychedelic landscape is host to all sorts of weird and wacky species

As you might expect, it’s a harsh place for most organisms [3]: There is no light below 1,000 m other than bioluminescence (the light produced by living organisms); there are high pressures that we cannot survive without specialised systems in place (due to being crushed, and other, gorier, things…); temperatures are pretty chilly (4°C); and it’s characterised by limited food availability, dependant on the ‘snow’ of debris from the surface waters above (or, less romantically, a large dead whale). Luckily though, life on earth has never needed circumstances to be easy to evolve and flourish. Astonishingly enough, this environment is known to be one of the most biodiverse in the world [4]. A dazzlingly myriad of creatures and organisms. Light spectacles are common in the majority of these deep-sea animals, making light the most common form of communication on the, misguidedly named, Planet Earth. This psychedelic landscape is host to all sorts of weird and wacky species. Floating in watery space, you might find a dumbo octopus whose fins resemble the large ears of Dumbo the Elephant; prehistoric Six-gilled Shark; Wolf-fish; Chaunax coffinfish, otherwise known as a frog fish, for its adorable frog like appendages… I could go on.


A unique and important habitat

Meanwhile, the habitats that exist here are excitingly unique. For example, there are chemosynthetic (i.e., a process of converting carbon molecules into organic matter; imagine photosynthesis, but without the light) habitats, such as hydrothermal vents and cold seeps (did you watch the Blue Planet II episode, with the brine pool and eels that got a toxic shock? That’s created by a cold seep). Here ‘hydrocarbon-rich fluids’ escape the earth’s crust and bubble into the ocean which supports many species [5]. To top it all off, it is thought that all life on earth originated from these vents [6]. Meanwhile another type of environment is found upon the soft sedimented seafloor, involved with vital functions and ecosystem services such as influencing ocean cycling and regulating atmospheric CO2 levels. For example, the Particulate Organic Carbon (POC) flux is crucial for carbon sequestration via the process of carbon burial.

We have unknowingly relied upon it since we increased our carbon dioxide output in the 1850s

Furthermore, this process has substantially increased since the onset of the industrial revolution [7] and we have unknowingly relied upon it since we increased our carbon dioxide output in the 1850s. Therefore, without the carbon burial taking place within the deep sea for the past century and a half, we would already have felt the full effects of climate change. Furthermore, science has shown how as terrestrial environments increase in biodiversity the number of key environmental ‘functions’ performed start to plateau [8], whereas in the deep, as the ocean floor rises in biodiversity, ecosystem functions increase exponentially [9]. This couldn’t send a clearer message about the importance of biodiversity on our ocean floors. If we disturb these deep-sea environments and reduce critical diversity, we handicap the important functioning’s that we are all completely dependant upon.


Deep-sea reliance

The deep is also relied upon for its productivity supporting fisheries; complex food webs originating there that maintain healthy marine ecosystems above; marine mammals, sea turtles and large predators relying on seamounts to feed and rest [10], and so on… What is fundamental to understanding the oceans, however, is comprehending just how interconnected they are [10]. On our terrestrial planet, we can deforest a landscape but be sure that on another continent, normal environmental processes are still occurring. Whereas, for the ocean, there are no such safety nets; the oceans are connected vertically, horizontally and globally. Essentially, it is important for everybody that no part of this is system is significantly disrupted. Otherwise, everything else, everywhere else, breaks down.

Why then, are we preparing to mine this landscape? What will the ramifications be of such industrial processes occurring in the deep? Catch the next article for answers to these questions on Deep Sea Mining.



  1. Tracey, D.M., Rowden, A.A., Mackay, K.A. and Compton, T., 2011. Habitat-forming cold-water corals show affinity for seamounts in the New Zealand region. Marine Ecology Progress Series, 430, pp.1-22.
  2. NOAA 2021, Ocean Exploration Facts. Accessed on 27/02/2021
  3. Thistle, D., 2003. THE DEEP-SEA FLOOR: AN OVERVIEW. Ecosystems of the deep oceans, p.5.
  4. Jobstvogt, N., Hanley, N., Hynes, S., Kenter, J. and Witte, U., 2014. Twenty thousand sterling under the sea: estimating the value of protecting deep-sea biodiversity. Ecological Economics, 97, pp.10-19.
  5. Joseph, A., 2016. Investigating Seafloors and Oceans: From Mud Volcanoes to Giant Squid. Elsevier.
  6. Dodd, M.S., Papineau, D., Grenne, T., Slack, J.F., Rittner, M., Pirajno, F., O’Neil, J. and Little, C.T., 2017. Evidence for early life in Earth’s oldest hydrothermal vent precipitates. Nature, 543(7643), pp.60-64.
  7. Fontela, M., Francés, G., Quintana, B., Álvarez-Fernández, M.J., Nombela, M.A., Alejo, I., Pedrosa, M.C. and Pérez, F.F., 2019. Dating the Anthropocene in deep-sea sediments: How much carbon is buried in the Irminger Basin?. Global and Planetary Change, 175, pp.92-102.
  8. Cardinale, B.J., Srivastava, D.S., Duffy, J.E., Wright, J.P., Downing, A.L., Sankaran, M. and Jouseau, C., 2006. Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature, 443(7114), pp.989-992.
  9. Danovaro, R., Gambi, C., Dell’Anno, A., Corinaldesi, C., Fraschetti, S., Vanreusel, A., Vincx, M. and Gooday, A.J., 2008. Exponential decline of deep-sea ecosystem functioning linked to benthic biodiversity loss. Current Biology, 18(1), pp.1-8.
  10. Fauna and Flora International, 2020. The risks and impacts of deep-seabed mining to marine ecosystems

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